FIELD OF THE INVENTION
This invention relates to the production of cooled and cleaned gaseous mixtures comprising H.sub.2, CO, CO.sub.2 and H.sub.2 O by the partial oxidation of liquid hydrocarbonaceous fuels or aqueous slurries of solid carbonaceous fuels. More particularly, it pertains to a process for cooling and cleaning synthesis gas with water to remove entrained particulate matter and includes flashing, deaerating, and energy efficient filtration of the gas cooling and scrubbing waters.
The partial oxidation process is a well known process for converting liquid hydrocarbonaceous fuels into synthesis gas, reducing gas and fuel gas. See coassigned U.S. Pat. Nos. 3,988,609. 4,251,228; 4,436,500; 4,468,376 and 4,704,137 for example, which are incorporated herein by reference. The raw effluent gas stream leaves the reaction zone at a temperature in the range of about 1100.degree. C. to 1540.degree. C. and comprises H.sub.2, CO, CO.sub.2 and H.sub.2 O along with minor amounts of other gases. Also included in the gas stream is entrained particulate matter in an amount in the range of about 1.5 to 500 /m.sup.3. In order to prevent contamination and/or plugging of beds of catalyst located downstream or to prevent plugging of burner nozzles, it is necessary to clean the raw gas stream by contacting it with water. Quench cooling the hot raw gas stream in water contained in a quench tank is shown and described in coassigned U.S. Pat. No. 4,801,347, which is incorporated herein by reference. Scrubbing the hot raw gas stream by means of a scrubbing nozzle or orifice scrubber is shown and described in coassigned U.S. Pat. Nos. 3,524,630 and 3,749,377, which are incorporated herein by reference. The solids concentration in the water used in gas quenching and scrubbing is in the range of about 0.1 to 6.0 wt. %. This water is called black water. It is pumpable and normally contains about 2.0 wt. % of particulate carbon. Removal of particulate carbon from the black water is commonly done by solvent extraction in a one or two-stage decanter, such as shown and described in coassigned U.S. Pat. No. 4,014,786. The carbon extraction system is complex and has a high capital cost due to its large number of equipment items, cost of solvent, as well as high energy cost. Steam consumption is high and heat exchange efficiency due to frequent fouling of the black water/grey water exchangers is poor. Thus, the most commonly used but costly solvent carbon extraction system is eliminated by the subject process. This arrangement eliminates the need for extraction naphtha and its associated high energy consumption.
The subject process removes the particulate matter and a portion of the sour gases from the gas cooling and scrubbing water stream in an energy efficient manner that also maximizes the quality and amount of deaearated grey water that is produced and returned to the raw gas quenching and scrubbing sections.